With continuous development of mobile communications technologies, a requirement for a positioning service is also increasing, and application scenarios of the positioning service are increasingly diverse, such as emergency assistance positioning, crime location tracing, navigation, and traffic control. However, regardless of how diverse the application scenarios are, a requirement of an industry for positioning is always to obtain a reliable, effective, and quick method; that is, a positioning technology that is easy to implement and highly accurate is always a user's most important requirement.
In observed time difference of arrival (OTDOA) positioning, a mobile station is used to receive a downlink positioning reference signal from multiple base stations and perform timing measurement, report time difference of arrival of PRSs between base stations, and perform calculation on a network positioning server to obtain a geographical location of the mobile station. A principle of the OTDOA positioning is as follows: User equipment (UE) detects and measures the positioning reference signals (PRS) to obtain a reference signal time difference (RSTD). Generally, a positioning server is used to configure the UE to complete the OTDOA positioning on a secondary cell (SCell).
In inter-band carrier aggregation (CA), a PCell and an SCell have different time division duplex (TDD) uplink-downlink configurations. As shown in FIG. 1, when a TDD configuration of the SCell is 1, each PRS opportunity on the SCell includes NPRS=4 PRS subframes, which are respectively subframes #1, #4, #5, and #9, and an interval at which the PRS opportunity occurs is 160 ms (that is, TPRS=160MS). However, when a TDD configuration of the primary cell (PCell) is 0, an SF #4 and an SF #9 are uplink subframes. Because the UE does not support simultaneous transmission and reception, the UE cannot receive a PRS signal on the SF #4 or the SF #9, thereby affecting accuracy of OTDOA measurement.
Therefore, during implementation of a CA scenario, positioning inaccuracy caused when different TDD uplink-downlink configurations are performed is an urgent problem that needs to be resolved.